# Create a .NET app in the App Engine flexible environment


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### Region ID

The `REGION_ID` is an abbreviated code that Google assigns
based on the region you select when you create your app. The code does not
correspond to a country or province, even though some region IDs may appear
similar to commonly used country and province codes. For apps created after
February 2020, `REGION_ID.r` is included in
App Engine URLs. For existing apps created before this date, the
region ID is optional in the URL.

Learn more
[about region IDs](https://docs.cloud.google.com/appengine/docs/flexible/dotnet/how-requests-are-routed#region-id).
<button class="devsite-dialog-close">OK</button>


> [!NOTE]
> **Note:** If you are deploying a new .NET web service to Google Cloud, we recommend getting started with [Cloud Run](https://docs.cloud.google.com/run/docs/quickstarts/build-and-deploy/deploy-dotnet-service).

This quickstart demonstrates how to create and deploy an app that displays a
short message.
You can use the sample application in this quickstart for any [supported](https://docs.cloud.google.com/appengine/docs/flexible/lifecycle/support-schedule#net) version of .NET, by specifying the runtime version
and operating system in your [`app.yaml`](https://docs.cloud.google.com/appengine/docs/flexible/dotnet/runtime#newversions) file.
By default, App Engine uses the latest available LTS .NET version if you don't
specify a runtime version in your `app.yaml` file.

## Before you begin

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### Required roles


To get the permissions that
you need to complete this quickstart,

ask your administrator to grant you the
following IAM roles:

- [App Engine Admin](https://docs.cloud.google.com/iam/docs/roles-permissions/appengine#appengine.appAdmin) (`roles/appengine.appAdmin`) on the project
- [Cloud Build Editor](https://docs.cloud.google.com/iam/docs/roles-permissions/cloudbuild#cloudbuild.builds.editor) (`roles/cloudbuild.builds.editor`) on the project
- [Storage Object Admin](https://docs.cloud.google.com/iam/docs/roles-permissions/storage#storage.objectAdmin) (`roles/storage.objectAdmin`) on the project
- [Logs Viewer](https://docs.cloud.google.com/iam/docs/roles-permissions/logging#logging.viewer) (`roles/logging.viewer`) on the project
- [Service Account User](https://docs.cloud.google.com/iam/docs/roles-permissions/iam#iam.serviceAccountUser) (`roles/iam.serviceAccountUser`) on the service account
- Ask your administrator to grant the following roles for the App Engine default service account:
  - [Artifact Registry Reader](https://docs.cloud.google.com/iam/docs/roles-permissions/artifactregistry#artifactregistry.reader) (`roles/artifactregistry.reader`) on the project
  - [Cloud Build Service Account](https://docs.cloud.google.com/iam/docs/roles-permissions/cloudbuild#cloudbuild.builds.builder) (`roles/cloudbuild.builds.builder`) on the project
  - [Storage Object Viewer](https://docs.cloud.google.com/iam/docs/roles-permissions/storage#storage.objectViewer) (`roles/storage.objectViewer`) on the project


For more information about granting roles, see [Manage access to projects, folders, and organizations](https://docs.cloud.google.com/iam/docs/granting-changing-revoking-access).


You might also be able to get
the required permissions through [custom
roles](https://docs.cloud.google.com/iam/docs/creating-custom-roles) or other [predefined
roles](https://docs.cloud.google.com/iam/docs/roles-overview#predefined).

## Additional prerequisites

1. Initialize your App Engine app with your project and choose its region:

       gcloud app create --project=[YOUR_PROJECT_ID]

   When prompted, select the [region](https://docs.cloud.google.com/appengine/docs/flexible/locations)
   where you want to locate your App Engine application.

   > [!CAUTION]
   > **Caution**: You cannot change an app's region once it has been set.

2. Install the following on your local machine:

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   - Install the [.NET Core SDK, LTS version](https://www.microsoft.com/net/download/core#/lts).

   - If you are using Visual Studio, you must use version 2015 or later. Images are available for [ASP.NET](https://www.asp.net/) Core apps written for .NET Core 1.0, 1.1, 2.0 and 2.1.

3. 

### App Engine locations

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App Engine is *regional* , which means the infrastructure that runs your apps is
located in a specific region, and Google manages it so that it is available
redundantly across
[all of the zones within that region](https://docs.cloud.google.com/docs/geography-and-regions).

Meeting your latency, availability, or durability requirements are primary
factors for selecting the region where your apps are run. You can generally
select the region nearest to your app's users, but you should consider [the
locations where App Engine is available](https://cloud.google.com/about/locations/#region)
as well as the [locations](https://cloud.google.com/about/locations/#region) of the other
Google Cloud products and services that your app uses. Using services
across multiple locations can affect your app's latency as well as its
[pricing](https://cloud.google.com/appengine/pricing).

You cannot change an app's region after you set it.

> [!NOTE]
> **Note:** Two locations, which are called `europe-west` and `us-central` in App Engine commands and in the Google Cloud console, are called `europe-west1` and `us-central1`, respectively, elsewhere in Google documentation.

If you already created an App Engine application, you can view its
region by doing one of the following:

- Run the `gcloud app describe` command.

- Open the
  [App Engine Dashboard in the Google Cloud console](https://console.cloud.google.com/appengine).
  The region appears near the top of the page.

<button class="devsite-dialog-close">OK</button> This quickstart assumes that you are familiar with building web apps with C#.

## Download the Hello World app

We've created a Hello World app for App Engine so you can quickly
get a feel for deploying an app to the Google Cloud.
The Hello World app is similar to the app created by Visual Studio when an empty
ASP.NET core app is created. The sample app adds an `app.yaml` file. The
`app.yaml` file is an App Engine configuration file that specifies your
runtime and other App Engine settings.

1. Clone the Hello World sample app repository to your local machine.

       git clone https://github.com/GoogleCloudPlatform/dotnet-docs-samples


   Alternatively, you can [download the sample](https://github.com/GoogleCloudPlatform/dotnet-docs-samples/archive/master.zip) as a zip file and extract it.
2. Change to the directory that contains the sample code.

          cd dotnet-docs-samples/appengine/flexible/HelloWorld

## Run Hello World on your local machine

1. Run the following commands from the `dotnet-docs-samples/appengine/flexible/HelloWorld/HelloWorld.Sample` directory:

       dotnet restore
       dotnet run

2. In your web browser, go to [http://localhost:5000](http://localhost:5000/).
   You can see the "Hello World" message from the sample app displayed in
   the page. In your terminal window, press <kbd>Ctrl+C</kbd> to exit the
   web server.

## Deploy and run Hello World on App Engine

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1. Run `gcloud app deploy` from the command line.
2. Launch your browser and view the app at `https://PROJECT_ID.https://docs.cloud.google.com/appengine/docs/flexible/dotnet/create-app#appengine-urls.r.appspot.com` `gcloud app browse`

This time, the page that displays the Hello World message is delivered by a
web server running on an App Engine instance.

**Congratulations!** You've deployed your first App Engine app to the
App Engine flexible environment!
If you encountered any errors deploying your application, check the [troubleshooting tips](https://docs.cloud.google.com/appengine/docs/flexible/testing-and-deploying-your-app#troubleshooting).

See the following sections for information about cleaning up as well as links to
possible next steps that you can take.

## Clean up

To avoid incurring charges, you can delete your Google Cloud project to stop
billing for all the resources used within that project.

> [!CAUTION]
> **Caution** : Deleting a project has the following effects:
>
> - **Everything in the project is deleted.** If you used an existing project for the tasks in this document, when you delete it, you also delete any other work you've done in the project.
> - **Custom project IDs are lost.** When you created this project, you might have created a custom project ID that you want to use in the future. To preserve the URLs that use the project ID, such as an `appspot.com` URL, delete selected resources inside the project instead of deleting the whole project.

1. In the Google Cloud console, go to the **Manage resources** page.

   [Go to Manage resources](https://console.cloud.google.com/iam-admin/projects)
2. In the project list, select the project that you want to delete, and then click **Delete**.
3. In the dialog, type the project ID, and then click **Shut down** to delete the project.

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## What's next

#### Learn the whole platform

Now that you know what it's like to develop and deploy App Engine apps,
you can explore the rest of Google Cloud. You already have the
Google Cloud CLI installed which gives you the tools to interact with
products like Cloud SQL, Cloud Storage, Firestore,
and more.

#### Learn about the App Engine flexible environment

Here are some topics to help continue your learning about App Engine:

- [An overview of App Engine](https://docs.cloud.google.com/appengine/docs/flexible/an-overview-of-app-engine)
- [Request routing](https://docs.cloud.google.com/appengine/docs/flexible/how-requests-are-routed)
- [Request handling](https://docs.cloud.google.com/appengine/docs/flexible/how-requests-are-handled)
- [Managing instances](https://docs.cloud.google.com/appengine/docs/flexible/how-instances-are-managed)

## Hello World code review

Hello World is the simplest possible App Engine app, as it contains only
one service, has only one version, and all of the code is located within the
app's root directory. This section describes each of the app files in detail.

#### `Program.cs`

The Hello World app is a simple ASP.NET app:

    var builder = WebApplication.CreateBuilder(args);
    var app = builder.Build();

    app.MapGet("/", () => builder.Configuration["My:Greeting"]);

    app.Run();

#### `app.yaml`

The [`app.yaml`](https://docs.cloud.google.com/appengine/docs/flexible/dotnet/configuring-your-app-with-app-yaml)
file describes the following configuration for your app:

- Sets `env: flex`, indicating your app uses the [App Engine flexible environment](https://docs.cloud.google.com/appengine/docs/flexible).
- Specifies the runtime used by the app.


      runtime: aspnetcore
      env: flex

      runtime_config:
        operating_system: ubuntu22

      # This sample incurs costs to run on the App Engine flexible environment. 
      # The settings below are to reduce costs during testing and are not appropriate
      # for production use. For more information, see:
      # https://cloud.google.com/appengine/docs/flexible/dotnet/configuring-your-app-with-app-yaml
      manual_scaling:
        instances: 1
      resources:
        cpu: 1
        memory_gb: 0.5
        disk_size_gb: 10

      env_variables:
        # The __ in My__Greeting will be translated to a : by ASP.NET.
        My__Greeting: Hello AppEngine!

  - For more information on how the .NET runtime works, see
    [The .NET runtime](https://docs.cloud.google.com/appengine/docs/flexible/dotnet/runtime).

  - For more details about how to design your app to take advantage of versions
    and services, see
    [An overview of App Engine](https://docs.cloud.google.com/appengine/docs/flexible/an-overview-of-app-engine).

  - For more details about the configuration settings for App Engine, see
    [Configuring your app with app.yaml](https://docs.cloud.google.com/appengine/docs/flexible/dotnet/configuring-your-app-with-app-yaml).